IOS will update dynamically the cost based on the number of active links in the bundle. If you don't want STP to converge in case you loose one of link of the bundle, you need to statically configure the cost for that bundle.
An internal formula is used to determine the default cost for an etherchannel which leads to the following default values:
2-ports GE bundle -> 3
3-ports GE to 7-ports GE bundle -> 2
8-ports GE bundle -> 1
2-ports 10GE bundle -> 1
If you want more granularity and still have the dynamic cost update, you can change the coding from 16bits to 32bits. In this case you will have a unique value based on the number of links and the speed of the link. You need to configurespanning-tree pathcost method longon the swith.
"IOS will update dynamically the cost based on the number of active links in the bundle"
Isnt that true just for LACP and not for PAgP?
Also, can you be a little more specific regaring the last part of your post? The 32-bit to 64-bit thing...
It's not LACP or PaGP that is dynamically updating, it is STP.
Currently STP uses 16bit numbers for cost. Because nowadays we can have multi-gigabit and 10Gbps links the granularity isn't really there with 16bit numbers so you can use 32bit numbering instead. Below is how the costs would change using 32bit numbering -
Hi everyone, I would like to thank you in advance for any help you can provide a newcomer like myself!
Im studying the 100-105 book by Odom and am currently on the topic of Port security. I purchased a used 2960 and I'm trying to follow a...
While deploying a number of 18xx/2802/3802 model access points (APs), which run AP-COS as their operating platform. It can be observed on some occasions that while many of their access points were able to join the fabric WLC withou...
I am going to design and build an LAN network under a tunnel underground with long distance between the switches.
I will have 2 Catalyst switches and 8 Industrial IE3000, and they will be connected with fiber.
For now I am planning on use Layer-2 s...